1. Field of the Invention
The present invention relates to an ice-cream machine, and particularly to an ice-cream machine having an evaporating pipe formed to closely contact an outer face of the cylindrical container.
2. Description of the Prior Art
In general, an ice-cream machine mixes material for ice-cream in a container by a mixing blade and cools the mixed material by a cooling apparatus disposed therein on the outer surface of the container, so that the ice-cream is made.
U.S. Pat. No. 4,583,863(issued to Alberto Pandolfi on Apr. 22, 1986) discloses a household ice-cream machine having an annular container 5 within which there is a mixing blade driven by a motor. FIG. 1 is a partially and schematically cross-sectioned view of a household ice-cream machine according to a first conventional household ice-cream machine. FIG. 2 is a partially and schematically cross-sectioned view of a household ice-cream machine according to a second conventional ice-cream machine. As shown in FIGS. 1 and 2, the annular container 5 is detachably supported within an annular vessel 1 so as to define an interspace 8 between the annular container 5 and the annular vessel 1. The annular vessel 1 contains such a quantity of a low-freezing point liquid as to fill the interspace 8 when the annular container 5 is assembled within the annular vessel 1. An evaporator 9 is disposed in a favorable heat exchange relationship with the liquid in the interspace 8. According to the first conventional household ice-cream machine, the evaporator 9 is housed within the interspace 8 so as to be immersed in the low-freezing point liquid when the annular container 5 is assembled in the annular vessel 1. The function of the low-freezing point liquid in the interspace 8 is to ensure good cold transmission from the evaporator 9 to the annular container 5. According to the second conventional household ice-cream machine, the annular vessel 1 is of material with a high thermal conductivity and the evaporator 9 is welded to the outer surface of the outer surface wall and the bottom of the annular vessel 1. Thus, the evaporator 9 is no longer immersed in the low-freezing point liquid, which further simplifies the periodic cleaning of the annular container 5. Moreover, the evaporator coil 9, even when the annular container 5 is removed, is protected and screened by the annular vessel and is invisible from the exterior.
However, the conventional ice-cream machines have a low heat-exchanging efficiency between the evaporator 9 and the annular container 5 because the evaporator 9 maintains a certain distance from the annular container 5. Also, the first conventional ice-cream machine has the evaporator 9 as like an evaporating pipe wound many times around an inner side of the annular vessel 1. Further, the second conventional ice-cream machine has the evaporator 9 as like an evaporating pipe wound many times around an outer surface of the annular vessel 1. The evaporating pipe must be wound with equal distance between each circumnavigates. Also, when the evaporating pipe is wound around the outer surface of the container, the evaporating pipe and the container are disposed under the condition of point contact. Thus, heat-exchange is not generated promptly.